For electrophotographic processes or electrostatic recording process, developers that visualize electrostatic images or electrostatic latent images may be classified into two-component developers and one-component developers. Two-component developers are composed of toner and carrier particles; whereas one-component developers are substantially composed of only toner. That is, one-component developers do not use carrier particles. One-component developers may be further classified into magnetic developers and nonmagnetic developers, in which magnetic developers contain a magnetic component while nonmagnetic developers do not. In addition, fluiding agents may be added to nonmagnetic one-component developers in order to improve the fluidity of the toner. Examples of fluiding agents include, but are not limited to, colloidal silica and the like.
In general, toners contain colored particles, which may be obtained by dispersing a pigment such as carbon black or other additives in latex. These toners may be prepared using either a pulverizing method or a polymerizing method. In the pulverizing method, a synthesized resin, a pigment, and optionally other additives, are melted, pulverized, and sorted to obtain particles having desirable diameters for use in the toner. In the polymerizing method, a pigment, a polymerization initiator, and optionally other additives such as cross-linking agents or antistatic agents, are uniformly dissolved in or dispersed into a polymerization monomer solution to provide a polymerization monomer composition. The composition may be dispersed into an aqueous dispersion medium containing a dispersion stabilizer, and the mixture may be stirred to provide microdroplet particles of the polymerization monomer composition. Subsequently, the temperature of the composition may be increased to provide a suspension of colored polymerization particles having the desired diameters for the polymerization toner.
Common image forming apparatuses include electrophotographic apparatuses and electrostatic recording apparatuses. In these apparatuses, an image may be formed by first exposing an image on a uniformly charged photoreceptor to form an electrostatic latent image. The toner may be attached to the electrostatic latent image through use of a transfer medium such as transfer paper or the like. The toner image may then be fused on the transfer medium using any of a variety of different methods including but not limited to heating, pressurizing, or applying a solvent vapor. In most fusing processes, the transfer medium with the toner image passes through fusing and pressing rollers, wherein the toner may be heated and pressed to fuse the toner image to the transfer medium.
Images formed by an image forming apparatus such as an electrophotocopier, should satisfy the requirements of high precision and accuracy. Toner used in an image forming apparatus may be obtained using a pulverizing method. According to this method, colored particles having a large range of sizes may be easily formed. To obtain satisfactory developing properties, the colored particles are sorted according to their size to reduce particle size distribution. However, it may be difficult to precisely control particle size and particle size distribution using conventional mixing/pulverizing processes. In addition, when preparing fine-particle toner, the toner preparation yield may be adversely affected by the sorting process. Also, there may be limits to the change/adjustment of toner design for obtaining the desirable charging and fusing properties. Accordingly, there is a need for a polymerized toner, the size of particles of which is easy to control and that does not require a complex manufacturing process such as sorting.